Luhn Algorithm Calculator

The Luhn Algorithm (Mod 10) Calculator is a simple tool allowing one to validate numbers and calculate the correct check digit for a given number via the Luhn checksum algorithm.

To utilize the instrument, enter the number (including the check digit) in the form below and click the "Verify & Calculate" button.

Luhn Algorithm Calculator

Number

Results

Write down the number:

Starting with the second-to-last digit and moving to the left, double every second digit:

If the result of the doubling is a two-digit number, add those 2 digits together:

Now add up all the digits together:

What Is the Luhn Algorithm?

The Luhn algorithm was named after the person who created it, a scientist named Hans Peter Luhn who worked for IBM. It is now commonly employed to verify various identification numbers, including IMEI digits and credit card numbers.

The Luhn algorithm, which is also frequently referred to as the Modulus 10 or the Luhn Formula, verifies the numbers within a given set of digits to evaluate whether the sum of those numbers is aligned with expectations or contains an error. After the algorithm has been applied, if the modulus 10 is equal to zero, the number is deemed to be valid and in accordance with the Luhn method.

Although the Luhn algorithm is often used to verify a range of different ID numbers, it is most frequently used to verify credit card numbers, and it is employed by all major credit card brands.